Container resistant to hydrocarbon materials

ABSTRACT

A container having resistance to hydrocarbon materials formed of a polyurethane having an elongation in excess of 200 percent at 65*F., the polyurethane being the reaction product of an organic polyisocyanate and a mixture of polytetramethylene azelate and polytetramethylene adipate and a diamine.

United States Patent Finelli Apr. 29, 1975 CONTAINER RESISTANT TO {56]References Cited HYDROCARBON MATERIALS UNITED STATES PATENTS [75]Inventor: Anthony F. Finelli, Akron, Ohio 3.004.939 10/1961 Varvaro260/75 [73] Assignee: The Goodyear Tire & Rubber FOREIGN PATENTS ORAPPLICATIONS p y Akron. Ohio 456,9ll 5/I949 Canada 260/75 NA [22] Filed:Jan- 14, 1974 822,532 l0/l959 United Kmgdom.... 260/75 NA PP Nod 433,133Primary ExuminerMelvyn I. Marquis Related US Application Data Attorney,Agent, or FirmF. W. Brunner; J. D. Wolfe [63] Continuation of Scr. No.378,115. July I0, i973,

abandoned, which is a continuation of Scr. No. [57] ABSTRACT 173.227.Aug. I9, I97], abandoned, which is a A container having resistance tohydrocarbon matericontinuation-in-part of Ser. No. 682.517, Nov. 13. 1 fd f a olyurethane having an elongation in I967. abandoned, which is acontinuation-in-part of excess of 200 percent at 5 the polyurethane Scr.No. 324,884, Nov. I9, 1963. abandoned. being the reaction product of anorganic polyisocya 't'd' t f ltt thl 'l't'd 52 0.5. Ci 260/75 NH;260/13; 260/3l.2 N; e y e y ene e 26()/32.8 N; 260/33.6 UB; 260/33.8 UB;260/37 N; 260/75 NK; 260/77.5 AM

Int. Cl C08g 22/10 Field of Search 200/37 N. 77.5 AM, 75 NH. 260/75 NKpolytctramethylene adipate and a diamine.

1 Claim, No Drawings CONTAINER RESISTANT T HYDROCARBON MATERIALS Thisapplication is a continuation of application Ser. No. 378,1]5, filedJuly I0, 1973, now abandoned, which was a continuation of applicationSer. No. 172,227, filed Aug. 19, 1971, now abandoned which was acontinuation-in-part of application Ser. No. 682,517, filed Nov. 13,1967, now abandoned, which was a continuation-in-part application ofSer. No. 324,884, filed Nov. 19, 1963, now abandoned.

This invention relates to a containerfor holding and transporting fuel,where the container is subjected to relatively high impact at lowtemperature.

More particularly, this invention relates to polyesterurethane fuelcontainers which have exceedingly good elongation properties at lowtemperatures; illustratively, in excess of 200% at 65F. in addition, thefuel containers of this invention exhibit adequate resistance to attackby solvents; i.e., it is not uncommon to have a solvent volume change ofless than about 30% on standing at 75F. for 96 hours in a mixture of 70%by weight of isooctane and 30% by weight of toluene.

Although such patents as US. Pat. Nos. 3,492,393

and 3,453,164 disclose how to make fuel containers of thepolyesterurethane type and containers of this type have achievedconsiderable commercial success, it was early appreciated that thecommercial containers made from these prior art compositions werelacking in low temperature properties, that is, the containers could notwithstand impact very well at extreme low temperatures. Consequently,many attempts have been made to improve the low temperature propertiesof these polyesterurethanes. One of the more successful efforts in thisendeavor is illustrated by US. Pat. No. 3,401,137, which discloses amixture of tetramethylene adipate and alkylene adipate where thealkylene radical contains 2 or 3 carbon atoms used to prepare thepolyesterurethane.

The polyesterurethanes of US. Pat. No. 3,401,137 have one significantdisadvantage, viz., the elongation of the material at 65F. is less than200% and thus it has been found to be unacceptable for use inpreparation of fuel cells to be used on certain classes of airplanes.Therefore, the fuel cells for this class of airplane have been builtwith conventional diene rubbers, using conventional techniques, withresulting higher costs and greater weight. It should be appreciated thatany unnecessary added weight is a serious disadvantage. As is generallyknown in the industry, for each pound of fuel cell weight that can beeliminated, the savings in fuel during the life of the cell in theairplane is approximately equal to the original cost of the fuel cell.

The polyesterurethanes prepared and used commercially are predominantlylinear molecules containing adipate groups. Although these polyurethaneshave excellent abrasion resistance, oil resistance, tensile strength andeven may be made essentially free of any tendency to become brittle attemperatures of as low as 60F., these polyurethanes do not have anelongation at -65F. in excess of 200%. Most of these have elongations ofabout 100% or less, consequently when these polyesterurethanes have beenused to fabricate fuel cells for operation at relatively lowtemperatures, the fuel cells have failed to withstand the normal impactforces experienced by fuel containers while being transported full ofgasoline or other hydrocarbon materials.

Therefore, it is an object of this invention to provide a method ofpreparing polyesterurethane fuel cell containers which have anelongation at F. of at least 200%.

The fuel cell containers of this invention are prepared frompolyurethane compositions obtained by reacting about 1.25 to 2.5 mols ofan organic isocyanate containing essentially two isocyanate groups withabout one mol of hydroxyl terminated polyester, said polyestercomprising at least about 20, and preferably 28, weight percent of apolytetramethylene azelate having a molecular weight of about 800 to3000 and preferably about 1000 to 2500 with about 0 to weight percent ofpolytetramethylene adipate having a molecular weight of about 800 to3000 and then reacting the excess isocyanate with about 0.5 to 0.9 molsof an aromatic diamine for each mol of polyisocyanate in excess of thatequivalent to the hydroxyl terminated polyester. The preferred ratio oforganic polyisocyanate to polyester is about 1.8 to 2.2.

Any suitable organic polyisocyanate may be utilized in the process ofthis invention, such as the following aliphatic diisocyanates: ethylenediisocyanate, propylene diisocyanate, tetramethylene diisocyanate,pentamethylene diisocyanate, octamethylene diisocyanate, undecamethylenediisocyanate, dodecamethylene diisocyanate and 3,3'-diisocyanatodipropylether, cyclopentylene-1,3-diisocyanate, cyclohexylene-l ,4-diisocyanate, and the aromatic diisocyanates; 2,4- tolylenediisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate,xylylene-l ,3-diisocyanate, 4,4'- diphenylmethane diisocyanate,2-nitrodiphenyl-4,4'- diisocyanate, 4,4'-diphenyl propane diisocyanate,pisocyanato benzyl isocyanate, m-phenylene diisocyanate, p-phenylenediisocyanate, naphthylene-l,4- diisocyanate, and3,3'-dimethyl-4,4'-diphenylenediisocyanate. The aromatic diisocyanatesare, however, preferred.

The aromatic diamines useful in this invention are used in the amount ofabout 0.25 to 0.9 mols per mol of excess organic polyisocyanate overthat equivalent to the polyester.- Preferred results are obtained whenthe amount of diamine is about 0.5 to 0.8 mols based on the excessorganic polyisocyanate. Representative examples of suitable aromaticdiamines where conventional techniques are to be used are the so-calledslow diamines as measured by the boiling methylene chloride test such asmethylene bis-ortho chloroaniline, ortho dichlorobenzidine,4,4'-bis-aminophenyl sulfone'. Representative examples of suitable fastdiamines as measured by the boiling methylene chloride test are4,4'-methylene dianiline, methyl tolidine, tolylene diamine, durenediamine, o-tolidine, o-dianisidine. Preferably, the fast diamines aredissolved in a suitable solvent before use.

Where 4,4'-diphenyl methane diisocyanate is used to react with themixture of hydroxyl terminated polyesters, it is preferred in some casesto use a monomeric polyol instead of the diamine. Representativeexamples of these polyols are glycerol, trimethylol propane, propyleneglycol, butane-diol and ethylene glycol.

The following examples illustrate the invention without, however,limiting it:

EXAMPLE I Polytetramethylene azelate (300 parts) having a reactivenumber of 58.7 was degassed under vacuum at 75C. for minutes, 55 partsofa commercial mixture of toluene diisocyanates containing 80% of the2.4- isomer and of 2,6-isomer. The reaction mixture was stirred atatmospheric pressure for 50 minutes at 7580C. to form the prepolymer.Then it was placed under vacuum for 30 minutes at 7480C. A mix of 31.8parts of 4,4-methylene bis-(Z-chloroaniline) and 15 parts of thepolytetramethylene azelate was added to the prepolymer with goodstirring. The clear fluid melt was poured into tensile molds (12 X 12 X0.05 inches) and then heated for 20 hours at 85C. On cooling, theelastomer had the following physical properties:

Shore A hardness 79 Tensile psi at 75F. 5400 Elongation 71 at 75F. 600Tensile psi at 65F. 7800 Elongation '7: at 65F. 350 Masland Bend Test OKat 90F. Volume change 1' 31.7

Although this polyurethane elastomer had over 200% elongation at 65F.its percent volume change indicates this polyurethane elastomer couldnot be used with highly aromatic fuels. Hence, this polyurethaneelastomer would be used to construct containers which were not to beused to hold liquids having solubility properties similar to those ofthe aromatic solvents.

EXAMPLE II A casting was prepared as in Example I from 400 parts ofpolytetramethylene azelate having a reactive number of 76.6, 96.5 partsof the 80%/20% mixture of 2,4 and 2,6-tolylene diisocyanate and 59 partsof 4,4- methylene bis (2-chloroaniline). The cured elastomer had thefollowing physical properties:

Shore A hardness 84 Tensile psi at 75F. 3800 Elongation '71 at 75F. 490Tensile psi at 65F. 7100 Elongation /1 at 65F. 230 Masland Bend Test OKat 9(lF. Volume Change 7:

EXAMPLE III Shore A hardness 78 Tensile psi at 75F. 5900 Elongation 71at 75F. 570 Tensile psi at 65F. 6700 Elongation 71 at -65F. 350 MaslandBend Test OK at -90F. Volume Change 71 27.6

EXAMPLE IV A casting was prepared from 300 parts of a polytetramethyleneazelate having a reactive number of 58.7, 300 parts of tetramethyleneadipate having a reactive number of 1 10, 158 parts ofa 80%/20% mixtureof 2,4- and 2,6-tolylene diisocyanate and 91 parts of 4,4-methylene-bis-(2-chloroaniline). The cured elastomer had the followingphysical properties:

Shore A hardness 9l Tensile psi at F. 7200 Elongation 7( at 75F. 490Tensile psi at -65F. 5700 Elongation 71 at 65F. 240 Masland Bend Test OKat -l00F. Volume Change 71 22.4

EXAMPLE V A casting was prepared from a liquid mixture of 300 parts of apolytetramethylene azelate having a reactive mixture of 58.7, 150 partsof a polytetramethylene adipate having a reactive number of l 10, 107parts of an %/20% mixture of 2,4- and 2,6-tolylene diisocyanate and 62parts of 4,4'-methylene-bis-(2-chloroaniline). The cast and curedelastomer had the following physical properties:

Shore A hardness 87 Tensile psi at 75F. 5700 Elongation 71 at 75F. 530Tensile psi at 65F. 8000 Elongation 7: at 65F. 340 Masland Bend Test OKat l00F. Volume Change 7: 25

The addition of the polyadipate ester to the polyazelate ester does notimpair the low temperature properties and yet results in improved fuelresistance as measured by the solvent volume change.

EXAMPLE VI A casting was prepared from 200 parts ofa polytetramethyleneazelate having a reactive number of 76.2, 200 parts of apolytetramethylene adipate having a reactive number of 55.8, parts of amixture of 2,4- and 2,6-tolylene diisocyanate and 52 parts of 4,4-methylene-bis-(2-chloroaniline). The cured elastomer had the followingphysical properties:

Shore A hardness 83 Tensile psi at 75F. 5400 Elongation 71 at 75F. 520Tensile psi at 65F. 6800 Elongation '7: at 65F. 360 Masland Bend Test OKat F. Volume Change '7: 22.5

EXAMPLE Vll A casting was prepared from 200 parts of apolytetramethylene azelate having a reactive number of 76.6. 200parts-of a polytetramethylene adipate having a reactive number of 11],I20 parts of a mixture of 2,4- and 2.6-tolylene diisocyanate and 77parts of 4,4- methylene-bis-(2-chloroaniline). The cast and curedelastomer had the following physical properties:

Shore A hardness 88 Tensile psi at 75F. 6600 Elongation 7: at 75F. 420Tensile psi at 65F. 7900 Elongation '71 at 65F. 330 Masland Bend Test OKat 90F. Volume Change "/1 l8 Tthe percent volume change was run by ASTMmethod D-47l-59T except the sample was allowed to stand immersed in thesolvent, a mixture of 70% isooctane by weight and 30% toluene by weight,for 4 days at 75F.

The reactive numbers of the polyester are expressed as the sum of thehydroxyl number and the carboxyl number but in general the carboxylnumber will be less than 5 and preferably less than 2.

EXAMPLE Vlll Table l 200F. for 22 hours. The cured elastomer was ahomogeneous translucent mass. The physical properties of the curedelastomer are given below:

Shore A hardness 85 Tensile psi at 75F. 5150 Elongation 71 at 75F. 580Tensile psi at 65F. l L570 Elongation at 65F. 366 Volume Change "/1 23.8Masland Bend Test OK at 80F. Crescent Tear (lbs/in) 319 Noerystallinity) EXAMPLE X A prepolymer was prepared from 350 parts of apolytetramethylene adipate having a reactive number of l l l, 150 partsof a polytetramethylene azelate having a reactive number of 59 and 149parts of a mixed tolylene diisocyanate. The prepolymer (200 parts) washeated to l60-l70F. Then the prepolymer was treated with a mixture of 28parts of methylene bisortho-chloroaniline and 7 parts of thetetramethylene azelate at 220F. After mixing well, the liquid mixturewas poured into molds. The cast specimens were treated at 203F. for 20hours before the translucent, homogeneous sheets were subjected tophysical testing.

Prepolymer Solution Physicals on'the Cured Sprayed Compositions SprayRecipes 1 and 2 l lnstron Tensile psi at 75F. 4300 Elongation 7! at 75F.460 Gauge, inches (0.02l Masland Bend Test OK at 90F.

Tensile psi at 65F. 7100 OK at 90F. 7300 Elongation at 65F. 290 290Volume Change '7: 21 20 Gehman Torsion Test C. 2l/40/-44 /39/44 Belowl00C. Below l00C. Crescent Tear (lbs/in) 500 390 Solution B was made bydissolving I72 parts of methylene his-ortho-chloroaniline with 206 partsof methyl ethyl ketone EXAMPLE [X A blend of 700 parts of apolytetramethylene adipate having a reactive number of 56 and 300 partsof a polytetramethylene azelate having a reactive number of 59 washeated to 200220F. and degassed under vacuum for minutes. 178 parts oftoluene diisocyanate was added to the mixture of degassed polyesters.After 30 minutes reaction the vacuum was applied again. Stirring undervacuum was allowed to continue for an additional 40 minutes. Theprepolymer so prepared was discharged into metal cans.

A urethane casting was prepared from 177 parts of the above prepolymerand 15 parts of molten methylene bis-orthochloroaniline. The sheets werecured at The results of the tests are listed below:

Shore A hardness 91 Tensile psi at 75F. 5350 Elongation 7! at 75F. 400Tensile psi at F. 8050 Elongation 71 at 65F. 280 Volume Change '71 l7.3Masland Bend Test OK at F Crescent Tear (lbs/in) 305 By the term fastamine crosslinkers" is meant those diamines which develop a turbidityinside of about 10 to less than 25 seconds with the boiling methylenechloride test. By this method essentially a saturated solution of thediisocyanate and diamine are each made up in methylene chloride. Thisusually gives about 0.2 to 0.5 molar solution of the diisocyanate andthe diamine when dissolved in methylene chloride. The boiling methylenechloride solutions of the diamine and the polyisocyanate are mixed andthen the time required to develop a turbidity is measured. Thosediamines which develop turbidity after 30 seconds are considered to beslow diamines.

When using the fast diamine it is preferred to dissolve the crosslinkerin a solvent or a carrier such as a plasticizer or extender oil ormaterials of a similar nature. Some suitable plasticizers are tricresylphosphate, tributoxy ethyl phosphate and dibutyl phthalate. Theseplasticizers can be used in amounts up to as much as about 50-60% of thepolyurethane. hence the fast diamines can be used to make castings withsuitable pressurized 2-component mixing equipment.

Any of the non-reactive solvents normally used in making paints whichare suitable for spraying may be used in this invention. Representativeexamples of these are benzene, toluene, the paraffmic naphthas, thenaphthenic naphthas, the aromatic naphthas, low boiling chlorinatedhydrocarbons such as methylene chloride. ethyl formate, propyl formate,butyl formate, amyl formate,.ethyl acetate, propyl acetate, methylacetate. butyl acetate, amyl acetate. acetone, methyl ethyl ketone,diethyl ketone, methyl isoamyl ketone, cellosolve acetate. cellosolvepropylate, methyl isobutyl ketone, dioxane, lower boiling nitro alkanes,etc. Mixtures of certain solvents in particular amounts may be desirableto obtain satisfactory spreading properties and evaporation rates whenthe polyurethane spray composition is applied to a surface. This isespecially true where very volatile solvents such as benzene and acetoneare used.

Also it is desirable to add to the spray composition certain pigmentsand other additives such as surface active agents, leveling agents, forinstance, cellulose acetate butyrate, and other additives well known tothe spray coating art. In particular, it is desirable to add about 0.5to 5 parts and preferably about 1 to 2 parts of a pigment on a hundredparts of prepolymer basis to improve the weather and reflectivecharacteristics.

Submicroscopic pyrogenic silica such as prepared in a hot gaseousenvironment by the vapor phase hydrolysis of silicon tetrachloride andavailable from Godfrey L Cabot. Inc. under the trademark CAB-O-Sil isespecially useful as a leveling agent in the sprayable polyurethanecompositions when used in about 0.1 to parts per l00 parts of solids inthe solution. The preferred amount is about 0.5 to about 6 parts as theamount of solvent needed to give a sprayable viscosity is not materiallychanged. Also, this range of pyrogenic silica gives good thixotropicproperties to the resulting sprayable composition.

With the more soluble crosslinkers the amount of carrier or solvent usedmay be as low as about 5 to 25% by weight and still with suitablepressurized mixing equipment films can be formed or castings can bemade. On the other hand, the very short pot life, i.e. 5 to secondsand/or less soluble diamines may require from to about 80% or even moreof the carrier to permit the reaction mixture to be sprayed or spread asa film or coating on cloth. Hence. the amount of carrier or solvent canconveniently be varied from a low of about 5% to in excess of 80% byweight to obtain the processing properties desired. A preferred range ofsolvent is from about 70% based on the mixture of polyester. diamine andpolyisocyanate as this range of solvents permit spray coating, spreadercoating and film spreading to be accomplished. The fast diamines listedon page 3 may be used to replace the diamine in Exam ples Vlll and theresulting fluid reaction mixture may be sprayed to form continuous filmsand to spread coat cloth provided the amount of carrier or solvent isadjusted and a pressurized two component spray gun or mixer is used toapply the material to the surface to be coated. In some instances thepressure may need to exceed about 1000 to 2000 pounds per square inchwhere the amount of solvent is less than about Normally there is no needto cure the fluid reaction mixture containing the fast diamines atelevated temperature as ambient temperature cures are adequate but thosereaction mixtures containing the slow diamines may need to be cured atelevated temperatures. Also, it has been found convenient and evenadvantageous in some cases to cure the reaction mixtures containing bothslow and fast diamines at elevated temperatures of about 40 to 160C. forabout l to 30 hours.

The Masland Bend Test is run on a strip of the cured polyurethaneelastomer 0.5 inches by 3 inches by 0.0l to 0.1 inch. The strip is bentback on itself to juxtaposition its ends on each other and then stapledin this position. The bent strip is mounted in a cold box and cooled tothe test temperature at a rate of about l0F. each 6 to 8 minutes. Thenthe sample is maintained at the test temperature, usually each l0interval from 30F. to the break point, for 1 hour, at which time thebent sample is subject to a quick below of 2.5 foot pounds. Thetemperature at which the sample breaks or shatters is taken as theMasland break point.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:

l. A container having resistance to hydrocarbon materials, as measuredby ASTM Method D-47l-59T of I less than 25 percent volume change formedof a polyurethane having an elongation in excess of 200 percent at 65F.,said polyurethane being the reaction product of a 1. 1.25 to 2.5 mols ofan organic polyisocyanate containing essentially toluene diisocyanatewith 2. 1 mol of a hydroxyl terminated polyester which comprises atleast 20 weight percent of a tetramethylene azelate having a molecularweight of about 800 to 3000 and about to 0 weight percent oftetramethylene adipate having a molecular weight of about 800 to about3000, and 3. 0.5 to about 0.9 mols of a diamine for each mol ofpolyisocyanate in excess of that equivalent to the hydroxyl terminatedpolyester.

1. A CONTAINER HAVING RESISTANCE TO HYDROCARBON MATERIALS, AS MEASUREDBY ASTM METHOD D-471-59T OF LESS THAN 25 PERCENT VOLUME CHANGE FORMED OFA POLYURETHANE HAVING AN ELONGATION IN EXCESS OF 200 PERCENT AT -65*F.,SAID POLYURETHANE BEING THE REACTION PRODUCT OF A
 1. 1.25 TO 2.5 MOLS OFAN ORGANIC POLYISOCYANATE CONTAINING ESSENTIALLY TOLUENE DIISOCYANATEWITH
 2. 1 MOL OF A HYDROXYL TERMINATED POLYESTER WHICH COMPRISES ATLEAST 20 WEIGHT PERCENT OF A TETRAMETHYLENE AZELATE HAVING A MOLECULARWEIGHT OF ABOUT 800 TO 3000 AND ABOUT 80 TO 0 WEIGHT PERCENT OF ATETRAMETHYLENE PATE HAVING A MOLECULAR WEIGHT OF ABOUT 800 TO ABOUT3000, AND
 3. 0.5 TO ABOUT 0.9 MOLS OF A DIAMINE FOR EACH MOL OFPOLYISOCYANATE IN EXCESS OF THAT EQUIVALENT TO THE HYDROXYL TERMINATEDPOLYESTER.
 2. 1 mol of a hydroxyl terminated polyester which comprisesat least 20 weight percent of a tetramethylene azelate having amolecular weight of about 800 to 3000 and about 80 to 0 weight percentof tetramethylene adipate having a molecular weight of about 800 toabout 3000, and
 3. 0.5 to about 0.9 mols of a diamine for each mol ofpolyisocyanate in excess of that equivalent to the hydroxyl terminatedpolyester.